1. Field of the Invention
The present invention relates to a swash plate type hydraulic system for use as a swash plate type hydraulic pump and hydraulic motor, and more particularly, to a swash plate type hydraulic system which includes a number of cylinder bores annularly arranged so that the transfer of a working oil is conducted between each of the cylinder bores and higher and lower oil passages concentrically defined in a cylinder block including a group of plungers slidably received in the cylinder bores during relative rotation between the cylinder block and a member supporting a swash plate engaging the protruding ends of the plungers, wherein a number of distributor valves are provided in the cylinder block in a radially arranged configuration for reciprocation between radially outer and inner positions to permit the respective cylinder bores to alternately communicate with the higher and lower pressure oil passages, and an eccentric wheel is provided eccentrically with respect to a center of rotation of the cylinder block to engage the distributor valves so as to permit each of the distributor valves to reciprocate with the relative rotation between the cylinder block and the swash plate supporting member.
2. Description of the Prior Art
In such a swash plate type hydraulic system, it is necessary to short circuit or interrupt the communication between higher and lower pressure oil passages depending upon required operation modes. Swash plate type hydraulic systems previously proposed by the assignee of the present patent application include control valve means exclusively used for such short circuiting and communication interrupting operations [e.g., see Japanese patent application laid-open No. 153057/86 (Japanese patent application No. 277816/84)].
In the above swash plate type hydraulic systems, both working oil distributing valves and control valve means are provided, becoming an obstacle to a compactness and a decrease in cost for the hydraulic system.